Just over two months ago, as CBS cameras swept in behind quarterback Josh Allen following the Buffalo Bills’ midseason win over the Kansas City Chiefs, Allen’s nemesis Patrick Mahomes — who is really more of a frenemy — appeared over his right shoulder.

Mahomes and the Chiefs had just lost to Allen and the Bills for the fourth time in five regular-season games, leaving Allen some distinctly gerrymandered bragging rights. As they approached each other for an embrace near midfield on that November night, Mahomes smiled knowingly. He might have been leaving another regular-season game against Allen with a defeat, but he also still had the edge where it counted most: 3-0 in the playoffs; three Super Bowl rings and counting to Allen’s zero. So it makes sense that when Mahomes saw Allen, he put a pin into the November defeat by uttering the words so many football fans — and arguably every single NFL executive — wanted to hear.

“We’ll do it again, baby,” Mahomes said, leaning into Allen’s ear.

It wasn’t a prediction. It was a promise.

This is the foundation of what fuels the Chiefs versus the Bills in Sunday’s AFC championship game — a Mahomes versus Allen subplot that has a chance to grow into a prolonged battle of story-tale significance in the league’s 104-year chronology. It’s maybe even to the point of being this era’s Tom Brady versus Peyton Manning, a defining quarterback rivalry that will live forever in the NFL’s ever-expanding fusion of history and mythology.

Bury the league. Freeze it over. Leave it for aliens to unearth in 10,000 years. Brady versus Manning will be the Achilles versus Hector of the NFL’s enduring legends.

Of course, Mahomes versus Allen isn’t quite on the level of Brady and Manning. Not quite yet. To have that kind of interwoven fabric between two careers, there has to be a consequential breakthrough that changes the landscape. At some point, both quarterbacks have to lose something meaningful at the hands of the other. Thus far, Allen and the Bills have lived up to only the lesser part of the equation — taking from Mahomes and the Chiefs repeatedly in the regular season but giving it all back when the two collide in the playoffs.

For Allen and the Bills, the postseason losses have always been particularly crushing. First in a 2020 AFC championship game that didn’t even seem as close as the 38-24 outcome. Then in the infamous “13 seconds” game in the 2021 divisional round, which saw the Chiefs mount a seemingly impossible late comeback before prevailing 42-36 in overtime. And finally, in the 2023 divisional round, which featured a consequential missed fourth-quarter field goal by Buffalo and a squandered home-field advantage in a 27-24 loss. That final defeat spawned Allen’s famously dejected “It sucks” postgame speech, marking a new low point in Buffalo’s battle to get past the Chiefs.

This is how it can go in these kinds of rivalries. For Manning — who will forever be considered one of the greatest pocket-passing quarterbacks in league history — the mounting pressure to finally beat Brady reached a boiling point after an 0-6 start. That included two brutal playoff losses, one of which saw Manning throw four interceptions in a 24-14 defeat in the 2003 AFC championship. In fact, it wasn’t until Manning’s eighth season in the NFL in 2005 that he finally dealt a loss to the quarterback who had become his archenemy. By then, Brady had two Super Bowl wins and was on track for his third later that season.

It turned out that Manning’s breakthrough was significant, too. He won his next three against Brady, culminating in his first AFC championship game win against Brady in the 2006 playoffs — helping to slingshot Manning to his first Super Bowl win just weeks later. Manning would never lose to Brady in the AFC title game again, notching two more after that. When it was all over, Brady would hold a career 11-6 record versus Manning, but a 2-3 record against him in the postseason, with all three Brady losses coming in the conference title game.

In the rear-view mirror, few really remember the regular-season clashes between Brady and Manning. Most everyone who watched their careers remembers the five playoffs battles, which stand as the most any two quarterbacks in league history have run into each other in the postseason. That’s more than any other iconic quarterback tandem has faced off, including the likes of Brett Favre versus Steve Young and Terry Bradshaw versus Kenny Stabler — each of whom met four times in the postseason.

For all those players, their quarterback counterpart essentially became their defining path to a Super Bowl win. More often than not, if you could get by your nemesis in the playoffs, you were on your way to the biggest Sunday stage.

Which is why it’s impossible to escape the final Super Bowl ring count between guys like Brady and Manning, a total which ended at 7-2 in Brady’s favor … but also featured the Manning family’s satisfaction of watching Peyton’s younger brother, Eli, knock Brady and Patriots off twice in the Super Bowl. A pair of victories that was punctuated by an Eli-led Giants team that denied the Patriots a perfect 19-0 record in Super Bowl XLII. Yet, even with Eli’s wins over Brady, you can’t help but wonder how many Super Bowls Peyton would have won if Brady never existed.

That’s all part of the lore. That and the friendship and respect that Brady and Manning have carried for each other since, even going so far as meeting in the 2009 offseason to secretly throw and train together for two days in a small Tennessee town. A generation of players who are now in their prime NFL years grew up on that rivalry and shared competitive admiration. And not surprisingly, Mahomes and Allen were among those watching, a fact that Mahomes attested to a year ago.

“I grew up watching [Brady versus Manning] games and remember how many memories I have from that,” Mahomes told reporters prior to meeting Allen in last year’s divisional round. “Hopefully we can play in these great games as well and give memories to the kids that come up behind us.”

To be sure, it’s a lot of history for Mahomes and Allen to follow. But until now, only Mahomes has assured his own personal chapters of greatness will endure. Allen has yet to appear in a Super Bowl, let alone win one. He’s never won an MVP award or been a first-team All-Pro. Indeed, at this intersection of his career, Allen could go on to become Manning to Mahomes’ Brady, winning a few here and there … or he could turn a corner Sunday and completely take over the rivalry … or he could continue to lose in his biggest postseason opportunities and end up being the Brady/Manning era’s Philip Rivers, who put up big passing numbers and plenty of wins, but never smashed through the competitive wall to reach a Super Bowl.

In a way, all of that is on the line for Allen this weekend. He can deny Mahomes’ quest to become the first quarterback in league history to win three straight Super Bowls — a feat not even Brady could accomplish — and in the process, gain entry to his own first Super Bowl opportunity. For this to truly be a rivalry that can rise to the level of Brady versus Manning, you could argue a win Sunday by Allen is a must. Anything less simply makes Allen and the Bills a familiar speed bump on the road to immortality.

In a way, the matchup even materializing is already a win for the NFL and the rest of us. Even fans who don’t count the Chiefs or Bills as their teams likely have a rooting interest in this one. Some will lean into the historic nature of what Mahomes is chasing and want to be counted among those who watched it happen with their own eyes. Others will lean into Kansas City having become a villain — the franchise and quarterback achieving enough to become hated for that success. Not to mention the perceived conspiratorial league biases that come along with it.

Still others will just want to see a great playoff show with a Super Bowl appearance hanging in the balance, either because they weren’t old enough to live through the heyday of Brady versus Manning, or because they want to see something like it again, if not better. And when the outcome settles, hopefully with an epic quarterback battle unfolding to achieve it, the end result will likely leave many with Mahomes’ words to Allen ringing in their ears as they look toward the 2025 season.

Do it again, baby.